The present invention relates to a permeability-enhancing carrier composition for topical pharmaceutical formulations and to topical pharmaceutical formulations which comprise a pharmacologically-active agent and the above carrier composition, and to methods for preparing such compositions and formulations.
It is well known in the art that the extent to which a topically-applied pharmacologically-active agent will penetrate into the skin and be further absorbed into the body is largely dependent on the type of carrier material, in the topical formulation, where it is applied and on the ability of this carrier material to penetrate into the skin. Triglycerides of fatty acids of medium or long chain length (chains containing about 6-18 carbon atoms) are known to enable pharmacologically-active agents to penetrate into the subepidermic layers of the skin. However, many pharmacologically-active agents are only poorly soluble in such triglycerides of fatty acids of medium or long chain length (about 6-18 carbon atoms), and because of this, their permeation into deeper layers of the skin takes place only to a limited degree and is slow and delayed. Further to the limited solubility of the pharmacologically-active agents in the triglycerides of fatty acids of medium or long chain length, the strong lipophilic properties of these triglyceride carrier materials also adversly affects the penetration into the skin of pharmacologically-active agents.